In cheese products, the state of the fat phase is important to the properties of the cheese. The fat phase is particularly important for the stabilisation of the cheese during production and ripening, but also for the final cheese to be used, eaten as such, or used in prepared ready-to-eat dishes e.g. pizza, toast or burgers.
Also, the oiling-off properties of cheese products is an important quality parameter. Oiling-off is the tendency to form free oil upon storage and melting. Excessive oiling-off is a defect most often related to heated products wherein cheese is used, e.g. pizza and related foods (cf. e.g. Kindstedt J. S; Rippe J. K. 1990, J Dairy Sci. 73: 867-873. It becomes more and more important to control/eliminate this defect, as the consumer concern about dietary fat levels increases. Free oil/fat in a product is perceived as a high fat content, and is generally undesirable.
In other food products the fat phase is often stabilised by mechanic emulsification, e.g. homogenisation. This technology is generally not applicable in cheese production as homogenisation of the cheese milk has a negative influence on the coagulation properties of the cheese milk and on the yield as well as the taste of the cheese produced therefrom.
In GB 1,525,929 it is disclosed as known to prepare stabilized oil-in-water emulsions using monoacyl glycero-phosphatide obtained by subjecting diacyl glycerophosphatide to the action of phospholipase A. GB 1,525,929 further describes use of phospholipase A treated phospholipoprotein-containing material for preparing oil-in-water emulsions, i.e. use of phospholipase treated material as an emulsion stabiliser for oil-in-water emulsions of which sauces, dressings and mayonnaise is mentioned. Cheese is not disclosed in GB 1,525,929.
So-called lecithinase activity, disclosed as phospholipase activity, has been reported for bacterial contaminants in milk, as well as the use of such milk for cheese production: “J. J Owens, Observations on lecithinases from milk contaminants, Process Biochemistry, vol. 13 no. 1, 1978, page 10-18” and “J. J Owens, Lecithinase Positive Bacteria in Milk, Process Biochemistry, vol. 13, page 13-15, 1978”.
U.S. Pat. No. 4,861,610 discloses a process for preparing a cheese composition, i.e. processed cheese, for incorporation into food material where monoacyl glycero-phospholipid, fat, water and molten salt is added to cheese. The process comprises a heating treatment to dissolve the cheese (the cheese being mixed with among others mono acyl glycero phospholipid) before the addition of fat. Subsequently the cheese-composition is emulsified by a mixer. U.S. Pat. No. 4,861,610 does not disclose treatment of milk with phospholipase and manufacturing of cheese from the enzyme treated milk.
There is a need for an improved process for the manufacturing of cheese, in particular a process for improving the stability of the fat in cheese.